 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/


 package org.eclipse.ui.texteditor;


 import java.util.ResourceBundle ;

 import org.eclipse.swt.events.HelpEvent;
 import org.eclipse.swt.events.HelpListener;

 import org.eclipse.jface.action.IAction;
 import org.eclipse.jface.util.IPropertyChangeListener;
 import org.eclipse.jface.util.PropertyChangeEvent;


 /**
  * Action used by an editor action bar contributor to establish placeholders in
  * menus or action bars which can be retargeted to dynamically changing actions,
  * for example, those which come from the active editor. This action assumes that
  * the "wrapped" action sends out property change events in response to state
  * changes. It uses these change notifications to adapt its enabling state and
  * its visual presentation.
  */
 public final class RetargetTextEditorAction extends ResourceAction {

     /** The target action. */
     private IAction fAction;
     /** The default label if there is no target action. */
     private String fDefaultText;
     /**
      * The local help listener
      * @since 2.1
      */
     private HelpListener fLocalHelpListener;
     /** The listener to pick up changes of the target action. */
     private IPropertyChangeListener fListener= new IPropertyChangeListener() {
         public void propertyChange(PropertyChangeEvent event) {
             update(event);
         }
     };

     /**
      * Creates a new action. The action configures its initial visual
      * representation from the given resource bundle. If this action's
      * wrapped action is set to <code>null</code> it also uses the
      * information in the resource bundle.
      *
      * @param bundle the resource bundle
      * @param prefix a prefix to be prepended to the various resource keys
      * (described in <code>ResourceAction</code> constructor), or
      * <code>null</code> if none
      * @param style one of <code>IAction.AS_PUSH_BUTTON</code>, <code>IAction.AS_CHECK_BOX</code>,
      * and <code>IAction.AS_RADIO_BUTTON</code>.
      *
      * @see ResourceAction#ResourceAction(ResourceBundle, String, int)
      * @see IAction#AS_CHECK_BOX
      * @see IAction#AS_DROP_DOWN_MENU
      * @see IAction#AS_PUSH_BUTTON
      * @see IAction#AS_RADIO_BUTTON
      * @since 2.1
      */
     public RetargetTextEditorAction(ResourceBundle bundle, String prefix, int style) {
         super(bundle, prefix, style);
         fDefaultText= getText();
         installHelpListener();
     }

     /**
      * Creates a new action. The action configures its initial visual
      * representation from the given resource bundle. If this action's
      * wrapped action is set to <code>null</code> it also uses the
      * information in the resource bundle.
      *
      * @param bundle the resource bundle
      * @param prefix a prefix to be prepended to the various resource keys
      * (described in <code>ResourceAction</code> constructor), or
      * <code>null</code> if none
      * @see ResourceAction#ResourceAction(ResourceBundle, String)
      */
     public RetargetTextEditorAction(ResourceBundle bundle, String prefix) {
         super(bundle, prefix);
         fDefaultText= getText();
         installHelpListener();
     }

     /**
      * Creates a new action. The action configures its initial visual
      * representation from the given resource bundle. If this action's
      * wrapped action is set to <code>null</code> it also uses the
      * information in the resource bundle. The action gets the given
      * action id.
      *
      * @param bundle the resource bundle
      * @param prefix a prefix to be prepended to the various resource keys
      * (described in <code>ResourceAction</code> constructor), or <code>null</code> if none
      * @param actionId the action id
      * @param style one of <code>IAction.AS_PUSH_BUTTON</code>, <code>IAction.AS_CHECK_BOX</code>,
      * and <code>IAction.AS_RADIO_BUTTON</code>.
      *
      * @see ResourceAction#ResourceAction(ResourceBundle, String, int)
      * @see IAction#AS_CHECK_BOX
      * @see IAction#AS_DROP_DOWN_MENU
      * @see IAction#AS_PUSH_BUTTON
      * @see IAction#AS_RADIO_BUTTON
      * @since 2.1
      */
     public RetargetTextEditorAction(ResourceBundle bundle, String prefix, String actionId, int style) {
         super(bundle, prefix, style);
         fDefaultText= getText();
         setId(actionId);
         installHelpListener();
     }

     /**
      * Creates a new action. The action configures its initial visual
      * representation from the given resource bundle. If this action's
      * wrapped action is set to <code>null</code> it also uses the
      * information in the resource bundle. The action gets the given
      * action id.
      *
      * @param bundle the resource bundle
      * @param prefix a prefix to be prepended to the various resource keys
      * (described in <code>ResourceAction</code> constructor), or <code>null</code> if none
      * @param actionId the action id
      * @see ResourceAction#ResourceAction(ResourceBundle, String)
      * @since 2.0
      */
     public RetargetTextEditorAction(ResourceBundle bundle, String prefix, String actionId) {
         super(bundle, prefix);
         fDefaultText= getText();
         setId(actionId);
         installHelpListener();
     }

     /**
      * Updates to the changes of the underlying action.
      *
      * @param event the change event describing the state change
      */
     private void update(PropertyChangeEvent event) {
         if (ENABLED.equals(event.getProperty())) {
             Boolean bool= (Boolean ) event.getNewValue();
             setEnabled(bool.booleanValue());
         } else if (TEXT.equals(event.getProperty()))
             setText((String ) event.getNewValue());
         else if (TOOL_TIP_TEXT.equals(event.getProperty()))
             setToolTipText((String ) event.getNewValue());
         else if (CHECKED.equals(event.getProperty())) {
             Boolean bool= (Boolean ) event.getNewValue();
             setChecked(bool.booleanValue());
         }
     }

     /**
      * Sets the underlying action.
      *
      * @param action the underlying action
      */
     public void setAction(IAction action) {

         if (fAction != null) {
             fAction.removePropertyChangeListener(fListener);
             fAction= null;
         }

         fAction= action;

         if (fAction == null) {

             setEnabled(false);
             if (getStyle() == AS_CHECK_BOX || getStyle() == AS_RADIO_BUTTON)
                setChecked(false);
             setText(fDefaultText);
             setToolTipText(""); //$NON-NLS-1$

         } else {

             setEnabled(fAction.isEnabled());
             if (fAction.getStyle() == AS_CHECK_BOX || fAction.getStyle() == AS_RADIO_BUTTON)
                super.setChecked(fAction.isChecked());
             setText(fAction.getText());
             setToolTipText(fAction.getToolTipText());
             fAction.addPropertyChangeListener(fListener);
         }
     }

     /**
      * Installs the help listener.
      *
      * @since 2.1
      */
     private void installHelpListener() {
         super.setHelpListener(new HelpListener() {
             public void helpRequested(HelpEvent e) {
                 HelpListener listener= null;
                 if (fAction != null) {
                     // if we have a handler, see if it has a help listener
 listener= fAction.getHelpListener();
                     if (listener == null)
                         // use our own help listener
 listener= fLocalHelpListener;
                 }
                 if (listener != null)
                     // pass on the event
 listener.helpRequested(e);
             }
         });
     }

     /**
      * The <code>RetargetTextEditorAction</code> implementation of this method declared on
      * <code>IAction</code> stores the help listener in a local field. The
      * supplied listener is only used if there is no handler.
      *
      * @param listener the help listener
      * @since 2.1
      */
     public void setHelpListener(HelpListener listener) {
         fLocalHelpListener= listener;
     }

     /*
      * @see IAction#run()
      */
     public void run() {
         if (fAction != null)
             fAction.run();
     }
 }

